This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Aer is receptor protein in E. coli that performs aerotaxis, that is it senses oxygen that modulates electron transport and proton motive force inside the cell. Unlike other receptors in this bacterium, Aer has a cytoplasmic PAS domain that binds FAD. We aim to explore the structure of this protein in detergents.